Control valve system

ABSTRACT

A pneumatic brake system that includes at least one pneumatic latching valve; a single device, such as a solenoid, for providing momentary pilot signals to pneumatic latching valve; a source of pressurized supply air in communication with the pneumatic latching valve; a spring brake or other pneumatic device in communication with the pneumatic latching valve; and, optionally, an indicator device for monitoring and displaying the state of the pneumatic latching valve. Upon receiving a first momentary pilot signal the pneumatic latching valve changes from closed to open and delivers pressurized air to the spring brake. Upon receiving a second momentary pilot signal, the pneumatic latching valve changes from open to closed and exhausts pressurized air from the spring brake to the external environment. The valve remains “latched” in its current state until the signaling device is energized and the next momentary pilot signal is received.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of the pending U.S. patentapplication Ser. No. 12/077,018 filed Mar. 14, 2008, which is acontinuation of U.S. patent application Ser. No. 11/066,591 filed Feb.25, 2005, now U.S. Pat. No. 7,354,118, the entire disclosures of whichare incorporated fully herein by reference.

TECHNICAL FIELD OF THE INVENTION

This invention relates in general to control devices for use withpneumatic or hydraulic systems, and in particular to a pneumaticlatching valve that utilizes a single solenoid valve or functionallysimilar device for achieving change of state.

BACKGROUND OF THE INVENTION

Solenoids are electromechanical devices often used to convert electricalenergy into mechanical energy and particularly into short strokemechanical motion. As such, solenoids are frequently utilized foractuating valves in response to an electrical signal. For certainapplications, valves must be positively maintained in predeterminedpositions to control the flow of gas or fluid through the valve. A firstsolenoid may be powered to positively move a valve to one position and asecond solenoid may be powered to positively move the valve member to apredetermined position and maintain it there until the second solenoidis de-energized and the first solenoid is energized to move the valvemember back to the other position. In situations where the valve is tobe retained in the actuated position for significant time periodswithout continuous power or a sustained control signal, latchingmechanisms may be used to hold the valve one position or the other. Aremotely controlled pneumatic latching valve may use two solenoids tochange operational states, i.e., supply to delivery and delivery toexhaust. Momentary activation of one solenoid actuates the pneumaticlatching valve to deliver supply air while momentary activation of theother solenoid actuates the pneumatic latching valve to exhaust thedelivered air pressure.

While basically effective for its intended purpose, the above-describedsystem configuration is problematic in that the use of two solenoids tochange the state of the pneumatic latching valve is expensive andredundant. Also undesirable is the additional size, weight, and plumbingcomplexity commonly found in this type of system. Thus, while theself-latching solenoid actuated pneumatic valves known in the relatedart have are generally useful, there continues to be a significant needfor smaller, less complicated, and less expensive pneumatic latchingvalves. Furthermore, especially in the case of vehicle braking systems,there continues to be a need for a latching valve that will not undergoa change of state if power to the solenoids is lost or interrupted.

SUMMARY OF THE INVENTION

Deficiencies in and of the prior art are overcome by the presentinvention, the exemplary embodiment of which provides a control valvesystem for use with vehicle air brake systems and other systems thatinclude pneumatic or hydraulic components. Thus, in accordance with afirst aspect of the present invention, a pneumatic brake system isprovided. This system includes at least one pneumatic latching valve; asingle device for providing momentary pilot air signals to the pneumaticlatching valve in fluid, i.e., pneumatic, communication with thelatching valve; a source of pressurized air in fluid communication withthe pneumatic latching valve; a spring brake or other pneumatic devicein fluid communication with the pneumatic latching valve; and anindicator device for monitoring and displaying the state of thepneumatic latching valve. Upon receiving a first momentary pilot signalthe pneumatic latching valve changes from closed to open and deliverspressurized air to the spring brake. Upon receiving a second momentarypilot signal, the pneumatic latching valve changes from open to closedand exhausts pressurized air from the spring brake to the externalenvironment. The valve remains “latched” in its current state until thesignaling device is energized and the next momentary pilot signal isreceived.

In accordance with another aspect of the present invention, a controlvalve is provided. This control valve is adapted to receive momentarypilot air signals from another device such as a single solenoid valve,for example, and changes from a first operational state to a secondoperational state in response to a first pilot air signal received fromthe solenoid valve. The control valve changes from the secondoperational state back to the first operational state only in responseto a second signal received from the solenoid. In this embodiment, anelectrically-powered solenoid valve acts as a “toggle switch” forchanging the operational state of the control valve.

In accordance with still another aspect of the present invention, apneumatic or hydraulic control valve is provided. This control valveincludes a valve body, which further comprises: (i) a supply port, atleast one delivery port, and at least one exhaust port; (ii) first andsecond pilot air inlets; (iii) a pilot air outlet; and (iv) an internalcavity comprising top, middle, and bottom chambers, wherein the topchamber is in communication with the first pilot air inlet and the pilotair outlet; the middle chamber is in communication with the supply port;and the bottom chamber is in communication with the delivery port, theexhaust port, and the second pilot air inlet. A first, or “select”piston is disposed within the top chamber and includes a bore thatpasses through its length. A biasing member is disposed within the topchamber beneath the select piston and urges the piston in an upwarddirection. A second, or “primary” piston is disposed within the top andmiddle chambers and defines an annular orifice therewith. Based on amomentary pilot signal input, the primary piston selectively engages theselect piston. A valve member or “inlet exhaust valve” is connected tothe bottom portion of the primary piston and a third or “auxiliary”piston is disposed within the bottom chamber beneath the valve member.In this embodiment, the various chambers are interconnected and, basedon the relative positions of the various pistons, permit the passage ofair from the supply port to the delivery port or from the delivery portto the exhaust port. The valve member is situated between the primarypiston and the auxiliary piston and opens or closes the internal supplyto delivery passageway.

Additional features and aspects of the present invention will becomeapparent to those of ordinary skill in the art upon reading andunderstanding the following detailed description of the exemplaryembodiments. As will be appreciated, further embodiments of theinvention are possible without departing from the scope and spirit ofthe invention. Accordingly, the drawings and associated descriptions areto be regarded as illustrative and not restrictive in nature.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a partof the specification, schematically illustrate one or more exemplaryembodiments of the invention and, together with the general descriptiongiven above and detailed description of the preferred embodiments givenbelow, serve to explain the principles of the invention.

FIGS. 1A-B are schematic block diagrams of an exemplary embodiment ofthe pneumatic brake system of the present invention.

FIG. 2 is a cross-sectional view of an exemplary embodiment of thecontrol valve of the present invention showing the valve in the offposition.

FIG. 3 is a cross-sectional view of an exemplary embodiment of thecontrol valve of the present invention showing the valve in the onposition.

FIG. 4 is a cross-sectional view of an exemplary embodiment of thecontrol valve of the present invention showing the valve in theintermediate or “ready” position.

FIG. 5 is a cross-sectional view of an alternate exemplary embodiment ofthe control valve of the present invention showing the valve in the offposition.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, a first exemplary embodiment of this inventionrelates to a pneumatic brake system that includes at least one pneumaticlatching valve 10; a single toggle-like control device 90 for providingmomentary pilot air signals to pneumatic latching valve 10 in fluid,i.e., pneumatic, communication with latching valve 10; a source ofpressurized supply air 92 in fluid communication with pneumatic latchingvalve 10; a spring brake 94 or other pneumatic brake device in fluidcommunication with pneumatic latching valve 10; and an indicator device96 for monitoring and displaying the state of the pneumatic latchingvalve. An electrically-powered solenoid in fluid communication with asource of pressurized air sufficient for creating a momentary pilot airsignal may be utilized for control device 90. Upon receiving a firstmomentary pilot signal the pneumatic latching valve changes from closedto open and delivers pressurized air to the spring brake. Upon receivinga second momentary pilot signal, the pneumatic latching valve changesfrom open to closed and exhausts pressurized air from the spring braketo the external environment. The valve remains “latched” in its currentstate until the signaling device is energized and the next momentarypilot signal is received.

With reference to FIGS. 2-5, control valve 10, which in the exemplaryembodiment is a pneumatic latching valve, includes a valve body 12,which further comprises: (i) a supply port 14, at least one deliveryport 16, and at least one exhaust port 18; (ii) first and second pilotair inlets 20 and 24; (iii) a pilot air outlet 22; and (iv) an internalcavity comprising top, middle, and bottom chambers, wherein top chamber26 is in communication with first pilot air inlet 20 and pilot airoutlet 22; middle chamber 28 is in communication with supply port 14;and bottom chamber 30 is in communication with delivery port 16, exhaustport 18, and second pilot air inlet 24. A first, or “select” piston 40is disposed within top chamber 26 and includes a bore 44 passing throughits length. A biasing member 50 is disposed within top chamber 26beneath select piston 40 and urges the piston in an upward direction. Asecond, or “primary” piston 60 is disposed within top chamber 26 andmiddle chamber 28 and defines an annular orifice 25 therewith. Based onthe momentary pilot signal input, primary piston 60 selectively engagesselect piston 40. A valve member 80 or “inlet exhaust valve” isconnected to the bottom portion of primary piston 60, and a third or“auxiliary/tripper” piston is disposed within the bottom chamber beneathvalve member 80. The embodiment of control valve 10 shown in FIG. 5includes a valve body 12 that is attachable to a pre-existing valve bodysuch as that of the PP-5 valve (Bendix Commercial Vehicle Systems,Elyria, Ohio). The PP-5 includes additional biasing member 61 whichreturns primary piston 60 to the “up” position when the internalpressure falls below a predetermined value. Thus, although not shown, asecond biasing member 61 may be included in the exemplary embodimentshown in the Figures for this purpose. Additionally, the control valvesystem disclosed herein is compatible with the electro-pneumaticlatching valve system disclosed in U.S. patent application Ser. No.10/784,171, the complete disclosure of which is hereby incorporated byreference.

In the exemplary embodiment shown in the Figures, each of the pistonsfurther includes a sealing member in the form of an o-ring encirclingthe piston body to create a substantially air-tight union with theinterior of valve body 12. Select piston 40 includes an o-ring 42,primary piston 60 includes an o-ring 62, and auxiliary piston 70includes an o-ring 72. These o-rings are dynamic and move with theirrespective pistons.

With reference to FIGS. 2-4, exemplary control valve 10 includes twobasic operational states: “on” and “off”, and an intermediate or “ready”state. Changing control valve 10 from on to off or vice versa isaccomplished by delivering a momentary pilot air signal, i.e., a briefburst of air, through a single solenoid, pilot control valve, or othersimilar device 90 to first pilot air inlet 20. By way of analogy, thefunction of control valve 10 is similar to the action of an ink penwhere one push of the button extends the ballpoint ink cartridge and asecond push of the same button retracts the ballpoint ink cartridge.

In the first operational state (see FIGS. 2 and 5), control valve 10 islatched in the closed, off, or released position, meaning thatpressurized air is not being delivered through the valve to spring brakeor other terminal device 94. In the closed state, select piston 40 is inthe “up” position within top chamber 26, primary piston 60 is in the“up” position within middle chamber 28 as is valve member 80, andauxiliary piston 70 is in the “up” position within bottom chamber 30.Supply air enters valve body 12, and the pressure differential betweenthe diameter of the middle chamber and the diameter of the narrowed areajust below supply port 14 maintains primary piston 60 in the “up”position such that the top edge of valve member 80, which may include arubberized disc, seats against the bottom of middle chamber 28 and formsa seal. This seal prevents pressurized supply air from passing throughthe body of control valve 10 to delivery port 16. In the closed state,any pressurized air in terminal device 94 or valve body 12 is exhaustedfrom control valve 10 through exhaust port 18.

In the second operational state (see FIG. 3), control valve 10 islatched in the open, on, or applied position, meaning that pressurizedair is being supplied to the valve from pressurized air source 92 anddelivered to pneumatic terminal device 94 through the body of controlvalve 10. In this open state, select piston 40 is momentarily in the“down” position within top chamber 26. In this position, shut-off seat46 forms a seal with the top portion of primary piston 60, pilot airoutlet 22 is blocked, and annular orifice 25 is eliminated. Becauseselect piston 40 is seated against the top of primary piston 60, theforce of the momentary pilot signal pushes both select piston 40 and theprimary piston 60 down within their respective chambers. This downwardmovement also pushes valve member 80 and auxiliary piston 70 into the“down” position. Because valve member 80 now forms a seal with exhaustseat 74, and is no longer sealed against the bottom portion of middlechamber 28, supply air entering control valve 10 at supply port 14passes through the body of the valve, exits through delivery port 16,and is delivered to terminal device 94. An internal pressuredifferential between o-ring 62 and the seal formed at exhaust seat 74maintains piston 60 and valve member 80 in the “down” position.

In the intermediate or “ready” state (see FIG. 4), control valve 10 istypically on, i.e., delivering air to pneumatic terminal device 94 dueto the positions of primary piston 60, valve member 80, and auxiliarypiston 70 within their respective chambers. To prepare control valve 10for the next change of state, a biasing member, referred to herein as“selection piston return spring 50” automatically returns select piston40 to the “up” position within top chamber 26. When select piston 40 isreturned to the “up” position in top chamber 26, the seal between thebottom portion of select piston 40 and the top portion of primary piston60 is eliminated. Select piston 40 no longer blocks pilot air outlet 22and annular orifice 25 is opened. The next momentary pilot signalreceived from device 90 (effecting a change of state) enters controlvalve 10 through first pilot air inlet 20, passes through select pistonbore 44, enters annular orifice 25, and is diverted out of the controlvalve through pilot air outlet 22. The pilot air is then directed backinto valve body 12 through second pilot air inlet 24 where it acts onauxiliary piston 70 and valve member 80 to return the valve to its offposition. Control valve 10 will not change state, i.e., move back intothe “on” position, until the next momentary pilot signal is received.

In the exemplary embodiment shown in FIGS. 2-5, control valve 10utilizes external plumbing for directing the pilot air signals into andthrough piston body 12. Although not shown in the drawings, thisplumbing can be in the form of tubes, conduits, or any other acceptablemeans for connecting the solenoid valve with the control valve and thevarious inlets and outlets with one another. In an alternate embodimentnot shown in the Figures, the external pilot air plumbing is replacedwith internal plumbing in the form of a passage that extends thought thebodies of primary piston 60, valve member 80, and auxiliary piston 70.In this alternate embodiment, pilot air outlet 22 is not included invalve body 12.

Because control valve 10 is either applied or released by momentarypilot air delivery from a single solenoid valve or the like, anindicator device 96 (see FIG. 1) may be incorporated into the system tomonitoring and report the operational state of the control valve. Thisdevice permits the system or vehicle operator to known whether thecontrol valve is in the applied or released state. In one embodiment,this device includes a double pole pressure switch (n.o./n.c.)controlling a double pole control switch. In another embodiment, apressure gauge placed in the delivery circuit provides the desiredinformation.

While the present invention has been illustrated by the description ofexemplary embodiments thereof, and while the embodiments have beendescribed in certain detail, it is not the intention of the Applicant torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. For example, the control valve and controlvalve system of the present invention may be utilized for or included inpneumatic systems, hydraulic systems, or systems that include bothpneumatic and hydraulic elements. Therefore, the invention in itsbroader aspects is not limited to any of the specific details,representative devices and methods, and/or illustrative examples shownand described. Accordingly, departures may be made from such detailswithout departing from the spirit or scope of the applicant's generalinventive concept.

What is claimed:
 1. A control valve for a pneumatic braking system,comprising: a pilot signal inlet for communicating with a controlpressure; a supply pressure inlet for communicating with a system supplypressure; an exhaust outlet for communicating with atmosphere; and adelivery outlet for communicating with an associated spring brake andselectively communicating with the exhaust outlet and the supplypressure inlet; wherein the supply pressure inlet communicates with thedelivery outlet to deliver system supply pressure through the controlvalve to release the associated spring brake when a first momentarypositive control pressure signal is applied to the pilot signal inlet;and the supply pressure inlet remains in communication with the deliveryoutlet until at least one of a second momentary positive controlpressure signal is applied to the pilot signal inlet or the systemsupply pressure air received at the supply pressure inlet is below apredetermined pressure, wherein the delivery outlet communicates withthe exhaust outlet to exhaust system supply pressure through the controlvalve to apply the associated spring brake.
 2. A control valve as inclaim 1 wherein the control valve delivers the system supply pressure tothe associated spring brake when the supply pressure inlet communicateswith the delivery outlet.
 3. A control valve as in claim 1 wherein thecontrol valve exhausts the system supply pressure from the associatedspring brake when the delivery outlet communicates with the exhaustoutlet.
 4. A control valve comprising: a pilot signal inlet port forcommunicating with a source of control pressure; a supply pressure inletport for communicating with a source of supply pressure; a deliveryoutlet port for communicating with a braking device; and an exhaust portfor communicating with atmosphere; and means for changing the controlvalve from a first operational state to a second operational state inresponse to a first momentary positive pilot control pressure signalreceived at the pilot signal inlet port; means for maintaining thecontrol valve in the second operational state when the first momentarypositive pilot control pressure signal is released; and means forchanging the control valve from a second operational state to the firstoperational state when at least one of a second momentary positive pilotcontrol pressure signal is received at the pilot signal inlet port orsupply pressure air below a predetermined pressure is received at thesupply pressure inlet port.
 5. A control valve for a pneumatic brakingsystem, comprising: a pilot signal inlet for communicating with acontrol pressure; a supply pressure inlet for communicating with asystem supply pressure; an exhaust outlet for communicating withatmosphere; and a delivery outlet for communicating with a spring brakeand selectively communicating with the exhaust outlet and the supplypressure inlet; and a valve member operative to move to a first positionupon receiving a first momentary positive control air pressure signalapplied to the pilot signal inlet and operative to move to a secondposition upon receiving a second momentary positive control air pressuresignal applied to the pilot signal inlet, wherein the valve member ismaintained in the first position when the first momentary positivecontrol air pressure signal is released and until the second momentarypositive control air pressure signal is received.
 6. The control valveas in claim 5, wherein the supply pressure inlet communicates with thedelivery outlet when the valve member is in the first position and thedelivery outlet communicates with the exhaust outlet when the valvemember is in the second position.